The present invention relates to chemical compounds that inhibit Mps-1 (Monopolar Spindle 1) kinase (also known as Tyrosine Threonine Kinase, UK). Mps-1 is a dual specificity Ser/Thr kinase which plays a key role in the activation of the mitotic checkpoint (also known as spindle checkpoint, spindle assembly checkpoint) thereby ensuring proper chromosome segregation during mitosis [Abrieu A et al., Cell, 2001, 106, 83-93]. Every dividing cell has to ensure equal separation of the replicated chromosomes into the two daughter cells. Upon entry into mitosis, chromosomes are attached at their kinetochores to the microtubules of the spindle apparatus. The mitotic checkpoint is a surveillance mechanism that is active as long as unattached kinetochores are present and prevents mitotic cells from entering anaphase and thereby completing cell division with unattached chromosomes [Suijkerbuijk S J and Kops G J, Biochemica et Biophysica Acta, 2008, 1786, 24-31; Musacchio A and Salmon E D, Nat Rev Mol Cell Biol., 2007, 8, 379-93]. Once all kinetochores are attached in a correct amphitelic, i.e. bipolar, fashion with the mitotic spindle, the checkpoint is satisfied and the cell enters anaphase and proceeds through mitosis. The mitotic checkpoint consists of a complex network of a number of essential proteins, including members of the MAD (mitotic arrest deficient, MAD 1-3) and Bub (Budding uninhibited by benzimidazole, Bub 1-3) families, the motor protein CENP-E, Mps-1 kinase as well as other components, many of these being over-expressed in proliferating cells (e.g. cancer cells) and tissues [Yuan B et al., Clinical Cancer Research, 2006, 12, 405-10]. The essential role of Mps-1 kinase activity in mitotic checkpoint signalling has been shown by shRNA-silencing, chemical genetics as well as chemical inhibitors of Mps-1 kinase [Jelluma N et al., PLos ONE, 2008, 3, e2415; Jones M H et al., Current Biology, 2005, 15, 160-65; Dorer R K et al., Current Biology, 2005, 15, 1070-76; Schmidt M et al., EMBO Reports, 2005, 6, 866-72].
There is ample evidence linking reduced but incomplete mitotic checkpoint function with aneuploidy and tumorigenesis [Weaver B A and Cleveland D W, Cancer Research, 2007, 67, 10103-5; King R W, Biochimica et Biophysica Acta, 2008, 1786, 4-14]. In contrast, complete inhibition of the mitotic checkpoint has been recognised to result in severe chromosome missegregation and induction of apoptosis in tumour cells [Kops G J et al., Nature Reviews Cancer, 2005, 5, 773-85; Schmidt M and Medema R H, Cell Cycle, 2006, 5, 159-63; Schmidt M and Bastians H, Drug Resistance Updates, 2007, 10, 162-81].
Therefore, mitotic checkpoint abrogation through pharmacological inhibition of Mps-1 kinase or other components of the mitotic checkpoint represents a new approach for the treatment of proliferative disorders including solid tumours such as carcinomas and sarcomas and leukaemias and lymphoid malignancies or other disorders associated with uncontrolled cellular proliferation.
Different compounds have been disclosed in prior art which show an inhibitory effect on Mps-1 kinase:
WO 2009/024824 A1 discloses 2-Anilinopurin-8-ones as inhibitors of Mps-1 for the treatment of proliferate disorders. WO 2010/124826 A1 discloses substituted imidazoquinoxaline compounds as inhibitors of Mps-1 kinase. WO 2011/026579 A1 discloses substituted aminoquinoxalines as Mps-1 inhibitors.
Substituted triazolopyridine compounds have been disclosed for the treatment or prophylaxis of different diseases:
WO 2008/025821 A1 (Cellzome (UK) Ltd) relates to triazole derivatives as kinase inhibitors, especially inhibitors of ITK or PI3K, for the treatment or prophylaxis of immunological, inflammatory or allergic disorders. Said triazole derivatives are exemplified as possessing an amide, urea or aliphatic amine substituent in position 2.
WO 2009/047514 A1 (Cancer Research Technology Limited) relates to [1,2,4]-triazolo-[1,5-a]-pyridine and [1,2,4]-triazolo-[1,5-c]-pyrimidine compounds which inhibit AXL receptor tyrosine kinase function, and to the treatment of diseases and conditions that are mediated by AXL receptor tyrosine kinase, that are ameliorated by the inhibition of AXL receptor tyrosine kinase function etc., including proliferative conditions such as cancer, etc. Said compounds are exemplified as possessing a substituent in the 5-position and a substituent in the 2-position.
WO 2009/010530 A1 discloses bicyclic heteroaryl compounds and their use as phosphatidylinositol (PI) 3-kinase. Among other compounds also substituted triazolopyridines are mentioned.
WO 2009/027283 A1 discloses triazolopyridine compounds and their use as ASK (apoptosis signal-regulating kinase) inhibitors for the treatment of autoimmune diseases and neurodegenerative diseases.
WO 2010/092041 A1 (Fovea Pharmaceuticals SA) relates to [1,2,4]-triazolo-[1,5-a]-pyridines, which are said to be useful as selective kinase inhibitors, to methods for producing such compounds and methods for treating or ameliorating kinase-mediated disorder. Said triazole derivatives are exemplified as possessing a 2-chloro-5-hydroxyphenyl substituent in the 6-position of the [1,2,4]-triazolo-[1,5-a]-pyridine.
WO 2011/064328 A1, WO 2011/063907 A1, and WO 2011/063908 A1 (Bayer Pharma AG) relate to [1,2,4]-triazolo-[1,5-a]-pyridines and their use for inhibition of Mps-1 kinase.
WO 2011/064328 A1 discloses compounds of formula S2:
in whichR1 is an aryl- or heteroaryl- group; wherein the aryl- or heteroaryl- group can be substituted inter alia with —N(H)C(═O)R6 or —C(═O)N(H)R6; in which R6 represents a hydrogen or a C1-C6-alkyl- group; the C1-C6-alkyl- group optionally being substituted with halo-, hydroxyl-, C1-C3-alkyl, R7O—. WO 2011/064328 A1 does not disclose compounds of the present invention as defined below.
WO 2011/063907 A1 discloses compounds of formula S1:
in whichR1 is an aryl group which is substituted at least one time; whereas the at least one substituent inter alia can be —N(H)C(═O)R6 or —C(═O)N(H)R6; in which R6 represents a group selected from C3-C6-cycloalkyl, 3- to 10-membered heterocyclyl-, aryl-, heteroaryl-, —(CH2)q—(C3-C6-cycloalkyl), —(CH2)q— (3- to 10-membered heterocyclyl), —(CH2)q-aryl, or —(CH2)q-heteroaryl, wherein R6 is optionally substituted, and q is 0, 1, 2 or 3;R2 represents a substituted or unsubstituted aryl- or heteroaryl- group;R3 and R4 inter alia can be hydrogen; andR5 represents a substituted or unsubstituted C1-C6-alkyl group.
WO 2011/063908 A1 discloses compounds of formula S3:
in whichR1 is an aryl group which is substituted at least one time; whereas the at least one substituent inter alia can be —N(H)C(═O)R6 or —C(═O)N(H)R6; in which R6 inter alia represents a group selected from C3-C6-cycloalkyl, 3- to 10-membered heterocyclyl-, aryl-, heteroaryl-, —(CH2)q—(C3-C6-cycloalkyl), —(CH2)q— (3- to 10-membered heterocyclyl), —(CH2)q-aryl, and —(CH2)q-heteroaryl, wherein R6 is optionally substituted, and q is 0, 1, 2 or 3;R2 represents a substituted or unsubstituted aryl- or heteroaryl- group;R3 and R4 inter alia can be hydrogen; andR5 is hydrogen.
There are patent applications which are related to [1,2,4]-triazolo-[1,5-a]-pyridines and their use for inhibition of Mps-1 kinase, but which have not been published at the time of filing of this patent application: Subject matter of the EP patent applications No. 11167872.8, and No. 11167139.2 as well as of the patent application PCT/EP2011/059806 are compounds of formula S4:
in whichR1 represents inter alia a phenyl- group which is substituted at least one time; whereas the at least one substituent inter alia can be —N(H)C(═O)R6; in which R6 inter alia can be —(CH2)q-aryl, wherein R6 is optionally substituted, and q is 0, 1, 2 or 3;R2 represents a substituted or unsubstituted aryl- or heteroaryl- group;R3 and R4 inter alia can be hydrogen; andR5 is hydrogen.
However, the state of the art described above does not specifically disclose the substituted triazolopyridine compounds of general formula (I) of the present invention, or a tautomer, an N-oxide, a hydrate, a solvate, or a salt thereof, or a mixture of same, as described and defined herein, and as hereinafter referred to as “compounds of the present invention”, or their pharmacological activity.
The above mentioned patent applications which are related to [1,2,4]-triazolo-[1,5-a]-pyridines mainly focus on the effectiveness of the compounds in inhibiting Mps-1 kinase, expressed by the half maximal inhibitory concentration (IC50) of the compounds.
For example, in WO 2011/063908 A1 the effectiveness in inhibiting Mps-1 kinase was measured in an Mps-1 kinase assay with a concentration of 10 μM adenosine triphosphate (ATP).
The cellular concentration of ATP in mammals is in the millimolar range. Therefore it is important that a drug substance is also effective in inhibiting Mps-1 kinase in a kinase assay with a concentration of ATP in the millimolar range, e.g. 2 mM ATP, in order to potentially achieve an antiproliferative effect in a cellular assay.
In addition, as one of ordinary skill in the art knows, there a many more factors determining the druglikeness of a compound. The objective of a pre-clinical development is to assess e.g. safety, toxicity, pharmacokinetics and metabolism parameters prior to human clinical trials.
One important factor for assessing the druglikeness of a compound is the metabolic stability. The metabolic stability of a compound can be determined e.g. by incubating the compound with a suspension of liver microsomes from e.g. a rat, a dog and/or a human (for details see experimental section).
Another important factor for assessing the druglikeness of a compound for the treatment of cancer is the inhibition of cell proliferation which can be determined e.g. in a HeLa cell proliferation assay (for details see experimental section).
Surprisingly it was found, that the compounds of the present invention are characterized by:                an IC50 lower than or equal to 1 nM (more potent than 1 nM) in an Mps-1 kinase assay with a concentration of 10 μM ATP, and        an IC50 lower than 10 nM (more potent than 10 nM) in an Mps-1 kinase assay with a concentration of 2 mM ATP, and        a maximum oral bioavailability (Fmax) in rat that is higher than 50% determined by means of rat liver microsomes as described below, and        a maximum oral bioavailability (Fmax) in dog that is higher than 45% determined by means of dog liver microsomes as described below, and        a maximum oral bioavailability (Fmax) in human that is higher than 45%, determined by means of human liver microsomes as described below, and        an IC50 lower than 600 nM in a HeLa cell proliferation assay as described below.        
Hence, the compounds of the present invention have surprising and advantageous properties. These unexpected findings give rise to the present selection invention. The compounds of the present invention are purposively selected from the above mentioned prior art due to their superior properties.
In particular, said compounds of the present invention may therefore be used for the treatment or prophylaxis of diseases of uncontrolled cell growth, proliferation and/or survival, inappropriate cellular immune responses, or inappropriate cellular inflammatory responses or diseases which are accompanied with uncontrolled cell growth, proliferation and/or survival, inappropriate cellular immune responses, or inappropriate cellular inflammatory responses, particularly in which the uncontrolled cell growth, proliferation and/or survival, inappropriate cellular immune responses, or inappropriate cellular inflammatory responses is mediated by Mps-1 kinase, such as, for example, haemotological tumours, solid tumours, and/or metastases thereof, e.g. leukaemias and myelodysplastic syndrome, malignant lymphomas, head and neck tumours including brain tumours and brain metastases, tumours of the thorax including non-small cell and small cell lung tumours, gastrointestinal tumours, endocrine tumours, mammary and other gynaecological tumours, urological tumours including renal, bladder and prostate tumours, skin tumours, and sarcomas, and/or metastases thereof.